Amplifying RF signals with time-varying amplitude (also referred to as “variable-envelope signals”) is not as power efficient as amplifying RF signals with constant amplitude (also referred to as “constant-envelope signals”). The reason is that power amplifiers utilized to amplify and transmit constant envelope signals could be more nonlinear (and hence more efficient) as compared to power amplifiers utilized to amplify and transmit variable envelope signals. On the other hand, communicating using RF signals with time-varying amplitude is more spectral efficient than communicating using RF signals with constant amplitude and as such most high-data-rate modern standards such as 802.11 Wireless LAN and cellular LTE and 5G use variable envelope signals.
In one existing solution, a variable amplitude signal is decomposed into two (or more) constant-amplitude signals, and the constant-amplitude signals are amplified using separate power amplifiers. A combiner is then used in the transmitter to combine the two amplified versions of the decomposed components, and the combined signal is then transmitted over the air by the transmitter's antenna. This method is generally known as linear amplification using nonlinear components (LINC), also known as outphasing. One shortcoming of this solution is that if the combiner is an isolating combiner, for example a Wilkinson combiner, some power will be lost in the resistor within the combiner due to the difference between the phases of the two outphasing components that are combined. Alternatively, if the combiner is a loss-less combiner, it will generally be non-isolating and the two power amplifiers feeding the combiner will modulate each other, which will reduce the linearity of the power amplifiers and hence increase the error vector magnitude (EVM) of the signal.
Thus, there is a need in the art to use phased array antenna panels, for example, phased array antenna panels with vertically-polarized probes and horizontally-polarized probes, to achieve a transmitter and a wireless communication system that overcomes the deficiencies in the art.